Comprehensive nutritional characterization, HPLC-QqQ-MS/MS phenolic profiling, and in vitro antioxidant and enzyme inhibitory activities of yellow kiwifruit (Actinidia chinensis) skin and bagasse.

Despite the increasing global consumption of yellow kiwi ( Actinidia chinensis ), the skin and bagasse generated during its processing remain largely undervalorized by-products with unexploited nutritional and bioactive potential. This study provides a comprehensive nutritional, and phytochemical characterization of yellow kiwifruit skin (YKS) and bagasse (YKB) to evaluate their potential for food valorization. YKB showed higher protein (6.12 vs. 4.56 g/100 g dw), lipid (5.72 vs. 0.58 g/100 g dw) contents and extraction yield (795.1 ± 6.1 vs. 574.4 ± 4.5 mg E t/g dw), whereas YKS exhibited higher mineral, total phenolic (30.28 ± 3.79 vs. 9.17 ± 1.70 mg GAE/g dw) and total flavonoid contents (359.16 ± 2.10 vs. 23.25 ± 1.02 μg QE/g dw). HPLC-ESI-QqQ-MS/MS analysis enabled the identification of 129 phenolic compounds, predominantly phenolic acids and flavonoids, revealing distinct phytochemical profiles between both by-products. YKS demonstrated higher antioxidant capacity, showing lower IC 50 values in the DPPH•, ABTS•+, superoxide radical, and nitric oxide scavenging assays, together with greater tyrosinase inhibitory activity (71% vs. 46% inhibition at 2 mg/mL). These preliminary findings suggest that both yellow kiwifruit processing residues possess potential as functional ingredients for food, nutraceutical, or cosmetic applications, paving the way for further research into their differentiated valorization.